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STEPHEN It. IIIRBY, OF EAST SAGINAW, MICHIGAN.

Letters Patent No. 103,896, dated June 7, 1870.

IMPROVEMENT IN ADJUSTABLE CURVE FOR SE OF DRAUGHTSMEN.

The Schedule referred to in these Letters Patent and making part of the same To all whom it may concern.-

Beit known that I, STEPHEN It. KIRBY, of East Saginaw, in the county of Saginaw and State of Michigan, have invented a new and useful Improvement in Circumiiexor and I do hereby declare that the following is a full, clear, and vexact description thereof, which will enable Yothers skilled in the art to make and nsemthe same, reference beingl had to the accompanyingidrawing forming part of this specification.

Thisinvention relates to a new andusefnl improvement in an instrument for describing regular and irregular curves, for obtaining the profile or face'of irregularly-curved or undulating surfaces, or curves and straight lines combined, and consists in the combination of adjustable trestle-work with a flexible rod or ribbon, and in connection therewith, an adjustable straight edge and connecting-rod, by means of which a series of parallel, irregular, or regular curves, either with or without straight lines, may be described, as will be hereinafter more fully described.

In the accompanying drawing l Figure 1 represents the instrument complete.

Figure 2 is a `longitudinal section, showing a portion of the trestlework and the straight edge and brace, the flexible rod being fixed orfastened so as to represent a straight line.

, t Figure 3- is a vertical section of fig. 2 on the 4line Similar letters of reference indicate corresponding' terial, to which are permanently attached, at regular distances apart, the short stands B, to which are pivoted the posts C andthe braces D of the trestle-.workg Tile posts C are formed double, as seen in lig. 3, so that the braces work between theparts.

E represents slots in these posts.

lhe ends'of the braces are connected together by the bolts F, so that the bolts, with the 'ends of the braces, will slip upand down in the slots for the adjustment of the rod or ribbon A. IVhen it is adjusted to the right o1' desired curve or shape, the nuts F are tightened on the posts, which fixes itin the desiredposition. In this manner the sheer of a ship, or the curve or shape of its side or bow, maybe exactly taken and transferred to either ship-timber or paper.

lhese instruments may be made of any size, so as to adapt l them to all the various purposes to which they may be applied. V G is -a slotted straight edge, jointed. to the edge of A, as seen at H. 4

I is a slotted connecting-rod, by which the straight edge is attached to the posts, as seen in fig. 1.

As represented inthe figure, the instrument may be moved along on the straightedge, and a succession of parallel lilies, corresponding with the curve of A, may be described.

In this example of my invention, A is a dat ribbon, which can he curved only in one direction or sideways. By employing a wire or similar rod instead of the flat ribbon, and attaching to it another set of tres tlc-work at right angles with that lseen in the drawing, the form or curve of two surfaces may be obtained at a single application, as the rod A will then be equally ilexible in all directions.

rlhis circumtlexor is applicable to a great variety of purposes, but in ship building, and for describing curved lines in draughting, it will be found invaluable.

The posts C may, it considered more convenient, be made single instead of double, as seen, and the slots E may be graduated, so thatran index of any kind, any particular curve,or curves of dierent or any particular radins may be described, without the use of any other instrument for that purpose.

The rod or ribbon A may also be graduated, so as t-o indica-te the longitudinal surface measurement of irregular curves or surfaces.

Having thus described my invent-ion,

I claim as new and desire to secure by Let-ters Patent- 1. The ribbon` or rod A, posts O, with the slots E, and braces D, combined with screw-bolts, arranged to operate substantially as and for the purposes herein -sl1own and described.

2. The combination of the slotted straight-edge G and slotted connecting-rod I with the ribbon or rod A, substantially as and for the purposes described.

STEPHEN It. IIRBY.

Witnesses:`

O.,W. Mower, W. J. Burrow. 

